关键词: 棉田, 害虫, 天敌, 生产力, 边缘效应

Abstract: An investigation was made on the soil seed bank at southeast edge of Tengger Desert with moss crust under natural and artificial vegetations. The results showed that the density of soil seed bank increased with the development of moss crust, which was 3.4 times higher under natural vege-tation than under 24 years old artificial vegetation. In the seed bank, a total of 12 species belonging to 6 families were identified, among which, annuals occupied more than 70%. No perennial seeds were found under artificial vegetation, but under natural vegetation, 20% of the seeds were of pe-rennials. As for semi-shrub seeds, they occupied 20% and 10% under artificial and natural vegeta-tion, respectively. Under artificial vegetation, the species richness index of soil seed bank was rela-tively lower, being about a half of that under natural vegetation. The species diversity index of the seed bank had a slight decrease with the development of moss crust under artificial vegetation, but increased to the maximum (0.693) under natural vegetation. The species similarity index was 1 among the seed banks under artificial vegetations, and 0.4 between those under artificial and natu-ral vegetation. The development of moss crust increased the roughness of surface soil and improved soil environment significantly, which could have positive effects on seed entrapment and plant establishment.

Key words: Cotton agroecosystems, Pest insects, Natural enemies, Edge effect